Factors Influencing Polymorphic Transition of Hyoscine N-Butyl Bromide

Abstract

Two crystalline forms of hyoscine N-butyl bromide (HBB) were identified and characterized by DSC, x-ray powder diffraction, scanning electron microscope and i.r. spectrophotometry techniques. DSC was the most useful method in differentiating the two polymorphs. The stable and metastable forms of HBB showed no significant variation in their x-ray and i.r. spectra. Melting points were 123.4 ± .5° and 143.6 ± .9° for the metastable and the stable forms respectively. Their purities exceeded 99% and their heat of fusion was obtained. While crystallization from methanol produced the metastable form, other solvents precipitated the stable form. Compression force transfered the metastable form into the stable form. Such transfere depended on the applied pressure. Mild trituration and ball milling had a negligible effect on crystalline transitions. Although storage at room temperature and at 55° converted the drug into its stable form, the two crystalline forms coexisted in the commercial samples of the same batch or different batches.